The objective of this proposal is to (a) gain an understanding of and implement non-invasive device based on the principles of pulsed photothermal radiometry (PPTR) for application in the treatment of port- wine stain (PWS) and (b) develop a more efficacious and safe treatment of PWS in the clinical setting. This will be a combined approach involving basic scientists, engineers and clinicians. The preceding goals will be accomplished by a research team at the Beckman Laser Institute and Medical Clinic (BLIMC), University of California, Irvine, under the direction of Dr. Nelson in collaboration with the Laser Biology Research Laboratory, University of Texas M.D. Anderson Cancer Center (UTMDACC) under the direction of Dr. Jacques. Studies are proposed at three levels: (1) in vitro phantom gel and model PWS experimentation; (2) in vivo studies on animal models; and (3) clinical trials on patients.